Governor switch for electric motors



De 9, 1930. F. MEYER 1,784,675

GOVERNOR SWITGH FOR .ELECTRIC MOTORS Filed Nov. 19. 1927 Patented Y Dec. 9, 1930 UNITED `STATES' PATENT OFFICE FRANZ MEYER, OF JENA, GERKANY, ASSIGNOR '.lO THE`FIRM OF CARL ZEISS, OF

. JENA, GERMANY I GOVERNOR SWITCH FOR ELECTRIC MOTORS Application filed November 19, 1927, Serial No. 234,473, and in Germany November 24, 1926.

The present invention relates to regulators of revolutions for electromotors in which ay switch is actuated by the centrifugal force, which becomes operative at a fiyball weight i coupled to the electromotor and subject to the counteraction of springs.

According to the invention a particularly good working of these regulators and consequently a particularly uniform speed of the D motor to be regulated may be attained if the flyloall weight be rendered rotatable about a vertical axis and the countersprings be so constructed and disposed that their sagging direction falls.into the direction ofthe axis 5 of rotation'of the flyball weight and that the centrifugal forces, arising during the revolution, do not cause a sagging of the springs transversely to the axis of lrotation. One may attain in this way that the position 0 of the movable part of the switch is almost only dependent upon the amount of the centrifugal force, operative at the flyball weights. Additional forces whose action upon the countersprings changesduring each revolution and which may thus give rise' to oscillations, are dispensed with in the new regulator. Such forces are not only for general reasons undesirable but, in addition, always difficult of predetermination with reu)spect totheir action and hard to. be controlled. Owing to the absence of such forces tbe new regulator may be comparatively easily adjusted to a speed to be predetermined. V

With the new regulator one may use as a counterspring, e. g. a cylindrical helical spring. In order to satisfy the above conditions, the said spring should be so disposed 'that its axial" direction, which with such a spring' coincides with the sagging direction, falls into the direction of the axis of rotation of the flyball weight, i. e. in particular in such a way that it coincides with the axis of rotation in order that the centrifugal i5 forces., arising at the spring itself during the revolution, compensate each' otherand do not bring abouta bend of the spring transversely to its axis, which would, of course, also vary m the sagging of the spring. s

A simplified suitable arrangement is attained by choosing as countersprings platesprings which are so disposed as to lie, when theregulator is in anloperative state, i. e. when they 4are in a stretched state, in a plane almost perpendicular to the axis of rotation of theflyball weight.

Figs. 1 to 3 of the annexed drawing show as an example a regulator according to the invention. Fig. 1 is a central sectional side View of the regulator. Fig. 2 is a cross section taken on line 2-2 of Fig. 1 and Fig. 3 is a detail section through the holding device of the flywheel weight. a possibility of carrying out the electric connection of the regulator to the motor to be regulated and Fig. 5 shows a modification of the regulator represented in Figs. 1 to 3.

In the regulator illustrated in Figs. 1 to 3 there is vertically supported in a casing, con'- sisting of a standard al, a cylindrical jacket a2 and a cover-plate a3, a shaft b,which carries at its lower end a bevel wheel b1 and above thereof a disc b2. On this disc is fixed a little standard c in which is fastened a short band c1 with one of its ends, while its other Fig. 4 represents end is fastened to a bell-crank lever d. The latter is constructed as a cylinder whose axis coincides with that of the shaft b. On. the upper part of the cylinder is xed a horizontal band e1 to which is joined a vertical metal band e2. On the band e2 there is fastened a screw-bolt e3 on which are screwed two nuts f1 and f2, forming the fiyball weight. These nuts are further held by a resilient metal band or plate g which is on the one hand screwed to the nut f1 and on Vthe other hand to a frame h, fixed on the disc b2.'

The band g allows small radial movements of the nuts f1 and f2 under the action of the centrifugal force. By such movements the body d is somewhat tilted in the plane of Fig.

1, the'band c1 thereby somewhat beingbent.

The bands 'e1 and e2 interposed between the body d-and the screw e3 form a connection allowing the said movements of the nuts f1- and f2 and of the body d to take' place. l At its lower end, the cylinder d carries two knife edges d1 with which it bears against two plate-springs l and 2, resting on four knife edgesia, i* .11 provided on the disc b2. Of

these knife edges those denoted by 4 and i are adjustable in elevation by means of screws j whereby the tension of the plate-springs can be varied. In the state shown the springs il and i2 have already sagged to such an extent as to be able to counterpoise the centrifugal force, arising at the -iiyball weight at the described -speed of revolution. In order to avoid any relaxation of the springs, the disc b2 is provided with a stop b3. The knife edges 4 and '6 which are carried by two little standards 7, are in addition displaceable with these standards by means of screws 8 and 9 as well as nuts 1 and @'11 in the longitudinal direction of the plate-springs so that also the effective length of these springs may be varied and a satisfactory astatic condition be attained. At the lower front of the cylinder al is also fixed a lever d2, which forms the movable part of the switch to be actuated by the regulator. The fixed part of this switch forms a screw- 7c, provided in a cross piece k1 which is disposed and insulated in the frame h. In order to attain a safe current-supply for the switch, two collector rings Z1 and Z2 are xed on the lower side of the disc b2 `on which rings slip two plate-springs m1 and m2 which are in their turn fixed on the standard a1. The springs m1 and m? are supplied from outside with current by means of the mains m3 and mit. The mechanical connection of the motor to be regulated with the shaft of the regulator takes place by a shaft n, which is provided on the one hand with a flange of coupling nl and on the -other hand with a bevel wheel n2, engaging in the bevel wheel b1 of the shaft of the regulator.

The electric connection of the regulator i with the motor to be regula-ted may be seen from Fig. 4. The motor is connected to the mains g1 and g2 of a network while disposing a starter o1 in front of the armature o and locating a regulating resistance p1 as well as a stationary resistance p2 in front of the exciting winding p. Parallel to the stationary resistance p2 there is disposed the switch d2, c of the regulator, so that in a closed s tate it short-circuits this resistance and on being opened switches in the same.'

The mode of operation of the regulator may be easily gathered from the drawing. If the shaft b be rotated, the pressure of the knife edges all upon the plate-springs 1 and 2 increases until the latter sag to such an extent that with the prescribed speed the two parts of the switch d2 and 7c touch each other easily. Thereby the way is open to the exciting current through the resistance p1 and over the switch d2, c whereby, however, the resistance of the branch current containing the switch-is yet comparatively high. If, e. g. the number of revolutions then exceeds the prescribed value, the pressure, with which the two parts of the switch bear against each other, is increased, so that ultimately the resistance p2 is completely shortcircuited. Thereby the power of the exciting current is increased and the number of revolutions reduced until the relative pressure of the parts of the switch has once more attained the normal value.

As is obvious, a change in the sagging of the springs 'il and 'i2 can only be brought about by centrifugal forces, which are operative at the fiyb'all weight f1, f2. Variations of the sagging by their own weight of the moved parts or by centrifugal forces, which become operative at the springs themselves, do not arise.

In the modified construction` of the .regu- *lator according to Fig. 5 the two platespringsz'1 and i2 are replaced by a cylindrical helical spring 1' whose tension may be varied by a screw s. i

I claim:

1. A speed regulator for electric motors, comprising a base member, a vertical shaft rotatably supported in this base member, means adapted to actuate this shaft, a frame connected to this shaft, a metal band fixed on the frame and on the fiyball weight in.

such a way that its fiat side lies vertically, a switch comprising two parts adapted to coact with each other, one of the said two parts being connected with the said iyhall weight, while the other is connected with the said frame, springs ldisposed in the said frame in such a position that their sagging direction falls into the direction of the axis of the said shaft, and means adapted to transmit forces from the flyball weight onto the said springs.

2. A` speed regulator for electric motors comprising a base member, avertical shaft rotatablysupported in this base member, means adapted to actuate this shaft, la frame connected to this shaft, a flyball weight,

vmeans for -connecting this flyhall weight to the said frame, these means allowing the flyball weight to move perpendicularly to the shaft, springs disposed in the said frame in such a position that their sagging direction falls into the direction of the axis of the said shaft, a bell-crank lever disposed in the frame and adapted'to act on the springs, g fiexible metal bands between this bell-crank lever and the liyball-weight, and a switch containing two parts adapted to coact with each other, one of the said two parts being connected with the said ,bell-crank vlever while the other one is connected with the said frame.

3. A speed regulator for electric motors comprising a base member, a vertical shaft rotatably supported in this base member, means adapted to actuate this shaft, a frame connected to this shaft, a iiyball weight, means for connecting this flyball weight to the said frame, these means allowing the flyball weight to move perpendicularly to the shaft, springs disposed in the said frame in such a osition that their sagging direction falls into the direction of the axis of the said shaft, a bell-crank lever disposed in the frame and adapted to act on the springs, two exible metal bands arranged one hehind the other and being disposed between the said bell-crank lever and the flywheel weight in such a manner that the flat sides of the one band are vertical and those of the other horizontal, and a switch containing two parts adapted to coact with each other, one of the said two parts being connected with the said bell-crank lever, while the other one is connected with the said frame.

FRANZ MEYER. 

